They’re among the most commonly prescribed medications in the world, generating sales of more than $27 billion in 2009. Statins, such as Lipitor (atorvastatin), Zocor (simvastatin) and Crestor (rosuvastatin), are very effective at lowering bad (LDL) cholesterol levels in the blood, reducing the risk of cardiovascular disease.

Now, a new Danish study suggests that statins may also improve survival in some cancer patients.

Cholesterol is a key component of cell walls and essential for cell growth. Consequently, cholesterol is also needed for rapid cancer cell proliferation. The Danish researchers theorized that a drug that interferes with cholesterol production might also slow down cancer cell multiplication and spread, so they set out to see if statins affect survival rates in those with cancer.

To test their theory, the researchers analyzed data on patients with cancer across the entire Danish population. They examined records from 1995 through 2009, comparing death rates among patients who had used statins before their cancer diagnosis with mortality among those who had never used statins.

Published in the New England Journal of Medicine, the report was based on nearly 300,000 cancer patients. Of the patients studied, almost 19,000 had regularly taken statins before they were diagnosed with cancer, and more than 275,000 had never used the drug.

Patients who regularly took statins prior to being diagnosed with cancer were, on average, 15% less likely to die from certain cancers than patients who didn’t take them. Statin users were also 15% less likely to die from any cause. Improved survival was observed for 13 types of cancer, ranging from an 11% reduced risk among pancreatic cancer patients to a whopping 36% reduction in mortality for patients with cervical cancer.

Other studies echo these findings; one study observed reduced mortality among patients with advanced prostate cancer who take statins, while other studies found a reduced rate of recurrence among patients with prostate or breast cancer.

However, it’s important to remember that statin use in people without cancer, who are taking the drug to lower their risk of cardiovascular disease, doesn’t influence the incidence of cancer. In other words, there’s no evidence that statins are cancer preventative.

The Danish study authors note that this was an observational study, and that many factors could have influenced the favorable outcomes, such as the homogeneity of the Danish study subjects and lack of control over some variables, like smoking history.

Researchers are now calling for randomized trials to determine if there’s truly a cause-and-effect relationship between statins and cancer survival.

The American Cancer Society says the results are encouraging, but cautions that it’s too soon to start recommending cancer patients take statins as part of a treatment regimen.